1. Field of the Invention
The present invention relates generally to a computer technology, and more particularly relates to a technique for performing a synchronizing process between databases by the use of a computer system.
2. Description of the Related Art
During shifting from an existing computer system to a new computer system executed for the purpose of increasing a processing capacity or the like, it is often employed that a business application used for updating a database may be gradually shifted from one fitting to the existing server to another fitting to the new server while continuing an operation of the existing server. In such shifting, business applications of the respective servers must independently update their own databases provided, respectively, for the existing and the new servers in a condition where both databases are always maintained to be equivalent to each other. In this configuration, in order to keep matching between the database of the existing server and that of the new server, a synchronizing process which reflects updating of the respective databases on each other must indispensably be done.
In general, as a conventional technique which performs a synchronizing process, as described in Japanese Unexamined Patent Publication No. 2002-366407, a technique utilizing a replica is widely used for closely reflecting updating made for a master database onto another database that is a replica of the master database.
However, in such conventional synchronizing process technique utilizing the replica database of the master database, a master-servant relationship is given to the two databases, and updating one database is one-sidedly reflected on the other database. For this reason, when the respective databases are independently updated, in the conventional synchronizing process, logical inconsistency may occur as follows. Specifically, a record changed by a business application may be overwritten by an updating content of another database. Furthermore, when a synchronizing process is performed in a state in which updating is performed for the respective databases so as to register records having the same key in the databases, double registration of the records having the same key might be performed. In addition, when the synchronizing process is performed in the state in which updating is performed for the respective databases to delete records having the same key from the databases, double deletion of the records having the same key might occur.
Therefore, taking into consideration the above conventional problems up to now, an object of the present invention is to perform a synchronizing process without causing logical inconsistency to occur between the databases even though independent updating of databases that are kept to be equivalent to each other has been done.